Electrical switch



June 26, 1928.

L. A. M. PHELAN ET AL ELECTRICAL SWITCH Filed March l, 1924 A Tron/wm.

sultng are,

, body,

, llkewise d i and break an electrical Patented J une 2,6, 1928.

UNITED Sres-rasr PATENT oFF I CE.

LOUISA. M. PHELAN AND CLIFFORD HOTCHKISS, 0F BELOIT, WISCONSIN, ASSIGNORS, BY DIRECT AND MESNE ASSIGNMENTS, TO ABSOLUTE CON -TAC-TOR CORPORATION,

a CORPORATION or INDIANA.

ELECTRICAL SWITCH.

Application led March 1,

Our invention relates to electrical switches and has special reference to electrical con tact making devices comprising spaced electrodes that are sealed into a closed container and are adapted to be brought into electrical conducting relation with one another through the agency of a movable conducting preferably a liquid, such as mercury, osed in said rcontainer, which upon being tilted is instrumental in performing the circuit closing or circuit opening functions of the Switchs More particularly, our invention relates to an. electrical contactor device of the character indicated above, wherein electrical contact making or breaking will always be efected between two or more bodies ofthe conducting liquid. In contact making devices of this type as heretofore used, the cir cuit is usually made or broken between the body of conducting fluid on the one side and an electrode of solid conducting material on the other. With such contactor devices as heretofore used, it has been our experience that the occurrence of arcing directly upon an electrode of solid conductive material will sooner or later` cause deterioration and eX- tensive pitting of such electrodes. Particles of th solid material will bedriven off or volatili ed and will thus not only greatly reduce or deform the electrode, but will furthermore contaminate the conducting fluid and the various insulating portions of the switch.

However, with the switch embodying our present invention 'all arcing directly vupon unprotected surfaces of solid conductive electrodes is avoided. In the device comprising this invention, the arcing takes place only between surfaces of the conductin liquid and' hence, if a portion of this liquid is driven oi or volatilized, no `permanent injury to the device will result, since upon cooling, the volatilized material will again become liquid and revert to its former condition.

The applicants are. well aware that attempts have previously been made to make circuit, between two bodies of conducting liquid' within a con-` tainer, but in all. such instances it'has been the usual practice to permit the make or break of the circuit, together with the reto occur directly on or closely the following speciiication 1924. Serial No. 696,279. adjacent to the container walls. This form of structure is very unreliable for making or breaking an appreciable quantity of current since the heat of the acing will very soon destroy the adjacent container wall and also effect the formation of/a conductive,- scum over the wall portion, which scum will short-circuit the switch. Furthermore, if such switches are hermetically sealed to eX- clude all oxygen or to retain a suitable insulating an inert atmosphere, the heat of arcing will soon suiliciently deteriorate the container wall to permit the entrance of air or the exhaustion of the inert atmosphere from the container.

In order to avoid the aforementioned defects of the prior devices when used on heavycurrents, with the structure embodying our present invention, the make and break and the consequent arcing are made to take place at a point widely spaced from the container walls, as well as from all other portions of the switch which may be subject to injury from the excessive heat. l

In order to achieve the foregoing advantages,.we have developed an electrode structure having an enlarged head portion which is spaced from the container walls and which is adapted to gather and hold suspended a drop ofr the conducting liquid so that when the main rbody of the conducting liquid is tilted, contacttween this suspended drop and the main body of liquid. Thesuspended drop of conducting liquid will therefore comprise the actual contactpoint of the electrode and Serve to protect the solid conductive portion I will be made or broken bethereof from actual exposureV to the arc and the excessiveheat.

Thebbjects and advantages above indi`A cated, as well as further aims of our invention, will become more fully apparent from in connection with the ing, in which- Y Figure 1 is a cross-sectional view taken longitudinally through the centeil of an electrical contactor embodying our invention;

Fig., 2 is a detail sectional view of an electrode as used inthe structure of Fig. l;

ig. 3 is a cross-sectional view taken longitudinally through the center of a modified form of electrical contactar embodying our accompanying drawinvention and claims taken 4isis Fig. 4 is a sectional view taken upon the line 4-4 of Fig. 3; and,

Fig. 5 isa sectional view similar to Figure 4 but showing a still further modification of the structure embodying our invention.

The contactor device shown in Fig. 1 comprises in a general way a container 10 of blown glass or other suitable insulating inaterial having contained therein a. pair of electrodes 11 and 12 and also a body of conducting liquid siich as mercury 13.

The electrodes 11 and 12 may be respectively provided witli leading-in Wires 14 and 15 sealed into the container in any suitable manner, such for example, as shown and described in Patent No. 1,598,875 of Louis A. M. Phelan and Clifford Hotchkiss, entitled Electrical apparatus.

As stated in the above prior application, the electrodes 11 and 12 should preferably be formed of a material which is inert in the presence of an electricarc under the conditions present in the device. In furtherance off' this end, the body of mercury is preferably refined to an unusual state of purity and the remaining space within the container may be filled with an inert gas. As shown in Fig. 1, the electrode 11 merelyr comprises stranded wires extending for a considerable distance along the container in a position where they will be submerged in the body of mercury- 13. This electrode may be joined to the leading-in wire 14 at a point 16 where the leading-in wire emerges from the glass. With the joint at this point all of the leading-in wire is protected by the glass from exposure within thel container-only the electrode wire which is inert under the conditions present, being exposed within the container.

The electrode 12 likewise may comprise a stranded wire connected at a point 17 to the leading-in wire 15 and terminated by Van enlarged electrode head in the form of a solid cylinder 18 having a cavity at 19 in its lower end. The cavity at 19 may take any desired form which will serveA to retain therein a drop of the4 conducting liquid such as indicated at 20. As here shown the cavity is symmetrical about the axis of the cy lindrical electrode head and is formed with a. cross-section of the shape of a segment. l In the operation of the contacter shown, the body of mercury 13 upon being tilted in the proper direction may submerge the electrode head 18 and then if the container is tilted in the opposite direction, the merwill recede from the electrode thus opening been made and broken in this manner for several times, it has been found that adrop of the mercury will adhere to the concave lower end of the electrode and thereafter each contact will be effected only between eral embodiments of the circuit. Aiter thecircuit has' ythe resulting bodies of the liquid, and the solid electrode head 18 will be protected from any direct effects of the arc. If a portion of the suspended drop 20 vbecomes volatized no permanent injury results .since the vapor will soon condense upon the cold walls of the container and then return to the main bodyof the conducting liquid.

Figures 3 and 4 illustrate a. modified construction embodying oiir invention wherein a plurality of the enlarged electrode heads 21 and 22 having concave ends are employed.

striking The use of the plurality `ot electrodes in this manner is especially desirable where the contact is designed to make and break heavy currents. f

Figure 5 comprises a sectional view similar to Figure 4, butshowing instead of a plurality of separate electrode heads a single large electrode 23 provided with a plurality of cavities, each of which is designed to retain a suspended drop of the conducting fluid as at 24.

In this modification, in order to provide leading-in wires of suitable curreiitcarrying capacity and at the same time to permit gas tight seals through the container wall to be made, a number of spaced conductor wires or bars as at 25, are used. This construction ermits the use of comparatively small con uctor bars or wires, and, therefore, reduces the liability of breakage of the container wall due to expansion or contraction'inl respect to thev conductors when the device is heated.

While we have shown" and described sevour invention. it is to be understood that many further modifications may be made therein without departing from the spirit and .scope of the ap pended claims and we desire that only such limitations shall be imposed upon our invention as are specifically pointed out in the claims and such as are required by the prior art.

Having thus described our invention, what we. claim as new and desire to secure Letters Patent in the United States, is:

1. In an electrical switch. a contact making and breaking electrode comprising a suspendeddrop of conducting liquid.

2. In an electrical switch, a contact making and breaking electrode comprising. a. drop of conducting liquid ci substantial. volume sus ended from and covering the lower end'o a solid conductive member.

3. An electrical switch com rising a tiltable container, two norma ly vertically spaced bodies of conducting liquid of substantial volume therein that unite to close a circuit upon tilting the container, one of said bodies being suspended from a conductive member to which it is attached by adhesiom y volume of mercury and ductive liquid therein that are each of substantial size and which upon tilting the container unite or separate at a point spaced from the container walls, one of said volumes constituting a suspended body of conductive liquid that attaches itself by adhesion to one of said electrodes, the other of said electrodes being adapted to engage with said other volume of mercury.

6. In a mercury switch, an electrode of solid conductive material formed in a shape v to retain in suspended relation a substantial y uid for contacting with said surface mass of mercury thereon as a contacting point.

7. An electrical switch comprising an hermetically sealed tiltable container, a main movable body of conducting liquid therein,

and an electrode for contacting with said body on tilting said switch, said electrode having a concave lower end upon which a portion of said body of conducting vliquid adheres in suspended relation.

8. In a mercury switch, an electrode of solid conductive material that is wetted by mercury under predetermined conditions, said electrode being formed with acavity to retain in suspended relation a substantial mass of mercury thereon as a' contacting point. v

9. In an electrical switch,`a contact making and breaking electrode for heavy currents comprising a plurality of suspended drops of conducting liquid.

10. An electrical switch comprising an electrode having a plurality of cavities at its lower surface, and a body of conductive liqat predeter ined times, said cavities serving to severa ly hold a portion of said body of conductive liquid in suspended position.

11. A tiltable electric switch comprising a container, a main body of mercury therein which is connected to one electric terminal of said switch, an electrode in said container for holding in a suspended position a second body of mercury which attaches itself to said electrode by adhesion whereby said `se'cv ond body of mercury is spaced from the walls of said container, said bodies of mercury being brought into circuit making and breaking relation on tilting said container whereby the electric circuit is made and broken at points spaced from the container walls, and means for connecting said suspended body of mercury and said electrode to another electric terminal of said switch.

12. A tiltable electric switch comprisinga` container, a mam body ofl mercury therein which is connected to one ele'ctriftrminal" of said switch, an electrode to which a.' Second body of mercury is held through the action of adhesion in suspended relation and spaced from the walls of said container, said bodies of mercury being brought into circuit making and breaking relation on tilting said container whereby the electric circuit is made and broken at points spacedy from the container walls, and means for connecting said suspended body of mercury and said electrode to another electric terminal in said switch.

13. An electric switch container, a main bod of mercury therein, which is movable on t e tilting of said container, means'for connecting said main body of mercury to one electric terminal of said switch, an electrode to which a second body of mercury is held through the action of'adhesion in suspended relation and spaced from the walls of said container, said bodies of mercury being brought into circuit making and breaking relation on tilting said container whereby the electric circuit is made and broken at said second body of mercu which is spaced from` the container walls, and means for connecting said suspended body of mercury and said electrode to another electrie terminal of said switch.

In witness whereof, we-have hereunto subscribed our names.

LOUIS A. M. PHELAN. CLIFFORD HOTCHKISS. 

